1. Field of the Invention
The present invention relates to a liquid-sealing type vibration-isolating device for supporting, for example, an engine of a vehicle on a vehicle body in a vibration-isolating manner, and more particularly, to a liquid-sealing type vibration-isolating device including a primary fluid chamber within an elastomer, so that its volume may be varied by a load, a subsidiary fluid chamber communicating with the primary fluid chamber through communication passage means, a fluid sealedly charged within both the fluid chambers, and a switch-over valve for changing the flow length or the flow diameter of said communication passage.
2. Description of the Related Art
There is such a conventionally known liquid-sealing type vibration-isolating device described in Japanese Utility Model Application Laid-open No. 122841/92.
This liquid-sealing type vibration-isolating device includes a variable-volume intermediate chamber with at least a portion thereof defined by a flexible membrane in order to prevent a sudden increase in dynamic spring constant during switching of the communication passage means. The primary fluid chamber is connected to the intermediate chamber when the communication passage means is switched from one state to another by a switch-over valve in accordance with an increase in the number of engine revolutions is increased.
In the above prior art liquid-sealing type vibration-isolating device, however, because it is necessary to provide the intermediate chamber having the flexible membrane, the number of parts is increased and, thus, the size of the entire device becomes undesireably large.
The present invention has been accomplished with the above circumstance in view, and it is an object of the present invention to reduce the number of parts and the size of the liquid-sealing type vibration-isolating device.